This invention relates to a complex magnetic head and a method for manufacturing a magnetic head core of a complex magnetic head and, more particularly, to a complex magnetic head for use in a floppy disk drive (hereinafter referred to as FDD) in which a high recording density head core (hereinafter referred to as a first head core) and a low recording density head core (hereinafter referred to as a second head core) are combined in a unitary structure and a method for manufacturing a complex magnetic head core.
The magnetic head for use in an FDD includes a complex magnetic head in which two head cores of different recording densities are combined into a unitary structure. This is because there are two types of floppy disc (hereinafter referred to as FD) as a recording medium, i. e., a high density FDD of 120 Mbytes and a low density FDD of less than 2 Mbytes and different head cores are needed for writing and reading these two different types of FD with a common FDD unit.
FIG. 15 illustrates a complex magnetic head disclosed in Japanese Patent Laid-Open No. 63-103468, in which reference numeral 1 is a complex magnetic head, 2 is a first head core, 21 is a first RIW core, 22 is a first R/W gap, 23 is a first erase core and 24 is a first erase gap. Reference numeral 3 is a second head core, 31 is a second R/W core, 32 is a second R/W gap, 33 is a second erase core and 34 is a second erase gap. Reference numeral 4 is a slider.
In order to manufacture the complex magnetic head 1, the first head core 2 and the second head core 3 are separately prepared. Then, the first head core 2 and the second head core 3 are bonded together with the slider 4 interposed therebetween. At this time, the first head core 2, the second head core 3 and the slider 4 are bonded together with an appropriate positioning so that the first R/W gap 22, the first erase gap 24 and the like have appropriate gap depths (not shown).
One example of a method for preparing a head core will now be described. FIGS. 16a to 16e are views explaining the manufacturing method for the head core disclosed in Japanese Patent Laid-Open No. 3-263602. The head core manufactured by this method is different from the first head core 2 or the second head core 3 shown in FIG. 15 in terms of configuration but is substantially the same in terms of its function. In the figures, reference numeral 40 is a first core material, 41 is a first magnetic base plate provided with first gap grooves 41 a and 42 is a non-magnetic base plate. Also, reference numeral 43 is a second core material, 44 is a second magnetic base plate provided with second gap grooves 44a and coil grooves 44b. Reference numeral 45 is a chip-shaped head core prepared by this process.
First, the first core material 40 of FIG. 16a and the second core material 43 of FIG. 16b are joined with their first gap grooves 41a and the second gap grooves 44a positioned in aligned opposition with each other so that a series of holes is formed between the first and second core materials 40 and 43 as shown in FIG. 16c. These holes defined by the first and the second gap grooves 41a and 44a are then filled with a fused glass material (not shown). As illustrated in FIG. 16c, the assembly is cut along dot-and-dash lines into the configuration illustrated in FIG. 16d, which then is sliced along dot-and-dash lines shown in FIG. 16d to obtain a head core 45 shown in FIG. 16e. 
When the head core is to be manufactured by the above-described conventional process shown in FIGS. 16a to 16e, a displacement can be easily generated between the first gap grooves 41a and the second gap grooves 44a when the first core material 40 and the second core material 43 are bonded and the track surfaces of the head core manufactured are often out of alignment. This misalignment may not cause any problem for the second head core for the low density FDD which has a track width of 125 xcexcm, but can significantly affect the recording and reproducing operation of the high density FDD which has a track width of 8 xcexcm. That is, when the first head core 2 is manufactured by the conventional process illustrated in FIG. 16, many of head cores manufactured have the above-mentioned fatal track misalignment, resulting in a low yield.
Upon manufacturing the complex magnetic head 1 shown in FIG. 15, the first head core 2, the second head core 3 and the slider 4 are to be bonded to each other with an appropriate positioning so that the first R/W gap 22, the first erase gap 24 and the like have appropriate gap depths (not shown), so that the fine positional adjustments which are complicated and difficult must be achieved, lowering the productivity of the magnetic head.
Accordingly, one object of the present invention is to provide a complex magnetic head free from the above-discussed problems of the conventional design.
Another object of the present invention is to provide a complex magnetic head in which no track surface displacement are generated.
Another object of the present invention is to provide a complex magnetic head in which gap depth of the head core can be easily controlled.
A further object of the present invention is to provide a method for manufacturing a magnetic head core of a complex magnetic head free from the above-discussed problems of the conventional technique.
With the above objects in view, the present invention resides in a method for manufacturing a magnetic head core of a complex magnetic head, comprising the steps of binding a first core material of a U-shaped cross section and a second core material of a flat plate shape to form a tubular core material having two bonded portions between the first and second core materials. Then, a plurality of grooves are formed in the tubular core material across one of the bonded portions to form a plurality of track surfaces. The grooves are then filled with a fused glass material, and the other of the bonded portions is removed to form a substantially U-shaped core block having a plurality of track surfaces separated by the glass-filled grooves. The U-shaped core block is then sliced along each of the grooves to obtain a plurality of magnetic head cores.
The step of filling the grooves with the glass material may include the step of forming a chromium layer on surfaces of the plurality of grooves before filling the grooves with the glass material to expedite the fusion of the glass material. The chromium layer may have a thickness of from 50 xcexcm to 300 xcexcm.
The glass material may be a powder glass to expedite the fusion of the glass material or may be in a ladder shape and may be applied with the track surfaces received within its openings.
The step of filling the grooves with the glass material includes the step of placing a head support member on a side surface of the core materials and binding the head support member with the core materials by the fusion of a glass material, and wherein the step of cutting the U-shaped core block along each of the grooves into a plurality of magnetic head cores includes the step of cutting the head support member upon the cutting of the U-shaped core block to provide a head support for the head core.
A complex magnetic head of the present invention comprises a planar base reference plate for providing a reference position, a first head core provided at its side portion with a first support portion positioned with respect to the reference plate and having provided at its leg portion with a first space portion, a first coil portion accommodated within the first space portion, a second head core provided at its side portion with a second support portion positioned with respect to the reference plate and having provided at its leg portion with a second space portion, a second coil portion accommodated within the second space portion, and a holder disposed between the first head core and the second head core, having its bottom portion mounted on the reference plate, having one of its side surfaces joined to the first support portion and having the other of its side surfaces joined to the second support portion, for holding the first head core and the second head core. The first support portion is joined to one of the side surfaces of the holder which extends for a predetermined length from a predetermined position of the reference plate, and the second support portion is joined to the other of the side surfaces of the holder which extends for a predetermined length from a predetermined position of the reference plate.
At least one of the first head core and the second head core may be provided with the head core manufactured by the above process and have a head support portion.
The side surfaces may have respective groove thereon to control the intrusion of a bonding agent bonding the holder to a first positioning portion and a second positioning portion.
The first coil portion and the second coil portion may be formed in an integral unitary structure.
The plurality of coil terminals provided at least on the first coil portion may be arranged in parallel to the direction of rotation of a magnetic disc.
The first holder may be provided with a hole portion made by a projection on a molding die for manufacturing the first holder or by a laser beam.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.